A general header for use in a wireless access system will hereinafter be described.
A medium access control protocol data unit (MAC PDU) for use in a medium access control (MAC) layer will hereinafter be described in detail.
A MAC layer (or a link layer) located below a second (L2) layer and a physical layer has been designed to use different protocols according to various wireless access systems, for example, a local area network (LAN), a wireless LAN, 3GPP/3GPP2, a wireless MAN, etc. Therefore, a header format of the MAC PDU is defined in different ways according to individual wireless access systems.
Example of MAC PDU Format
FIG. 1 shows an example of the MAC PDU format for use in an IEEE 802.16e system acting as one of the wireless access systems.
Referring to FIG. 1, a MAC PDU may include a generic MAC header (GMH) field, a payload field, and a cyclic redundancy check (CRC) field. The generic MAC header (GMH) is used for data transmission between individual nodes at a link layer. The generic MAC header (GMH) may include a MAC address or a link address, and may include a header error check and control information of a link layer.
The payload indicates a specific part including actual data to be transmitted at a MAC PDU. In addition, CRC indicates a scheme for determining a check value used for checking the presence or absence of an error in transmission data when data is transmitted over a network or the like. However, the payload and the CRC may be optionally contained in a MAC PDU, whereas the generic MAC header (GMH) is always contained in the MAC PDU.